There are three kinds of water injection pumps used in peripheral oilfield development, electric submersible pumps, plunger pumps and centrifugal pumps. From the field application, its efficiency and working conditions are quite different. The plunger pump has the highest efficiency and the water injection is the lowest, especially the independent block and the oil field which can not form the water injection network. The plunger pump plus the frequency converter is an ideal choice.
The different working principles and characteristics of plunger pump and centrifugal pump decide their ideal application scope. The centrifugal pump is suitable for water injection blocks whose flow is greater than or equal to 3000m3 / D. The plunger pump is suitable for water injection blocks whose flow is less than or equal to 2000m3/d. The most important problem in the selection of water injection pump for a water injection station is the investment and voltage level of the distribution system.
Centrifugal pumps and plunger pumps are widely used as two types of water injection pumps.
1. centrifugal pump
As far as the known high-pressure water injection centrifugal pumps in China are concerned, the displacement is between 60 and 400m3/h and the lift is about 1800m, and the efficiency of the nameplate is 45% to 79%. As we all know, the pump efficiency of the centrifugal pump is proportional to its displacement, and its lift is in inverse proportion, that is to say, the same pump, the pump efficiency increases with the increase of displacement, and decreases with the increase of the lift.
The operation of centrifugal pump is characterized by large displacement and low lift head, and relatively stable injection pressure. According to the requirements of the industry standard, combined with the operation capacity of the centrifugal pump in China, it is suggested that the application range of centrifugal pump is that the flow rate is not less than 30000m3/d, the water injection pressure is not more than 18MPa, and the injection pressure is relatively stable. It is possible to select the centrifugal pump to achieve the qualified index of energy saving monitoring for the water injection system.
2. plunger pump
With the improvement of the performance of the domestic piston pump, the efficiency of the plunger pump is more and more popular. The plunger pump is reciprocating from the plunger in the steel sleeve to discharge water, and the displacement is very small. If the flow is increased too much, the diameter of the cylinder liner and the plunger will be increased, so the pulse motion of the plunger will increase, which leads to the larger vibration of the pump body and the shortening of the life of the plunger pump. As far as the current usage is concerned, the general displacement is below 1500m3 / h, and the ideal displacement is about 1000m3/h. Under this condition, the piston pump runs smoothly and has a long life. The operation of the plunger pump is characterized by small displacement, high lift and high efficiency, and the pump efficiency is generally over 80%.
Because of the more vulnerable parts of the plunger pump, the specification requires that the standby coefficient is higher than that of the centrifugal pump, and 3 sets of plug pumps should be operated, with 1 standby units. The reasonable injection volume of plunger pump is less than 2000m3/d.
The injection pressure of plunger pump is not limited in principle, and it changes with the change of injection pipeline and formation pressure. The application condition of the plunger pump is that the flow rate is not more than 2000m3/d, which is suitable for the unstable water injection block, or the water injection development at the initial stage of the new area.
When the water injection pressure is certain, when the water injection is more than 3000m3/d, if the plunger pump is selected, one is to choose the plunger pump with large displacement. Two is the need to increase the number of the plunger pump to satisfy the quantity. This will increase the maintenance and maintenance of the plunger pump, and cause the difficulty of the management.